1. Field of the Invention
The present invention relates generally to optical and electronic devices, and, more particularly, to processes for improving the optical properties of GaInSb/InAs materials employed in infrared lasers and detectors.
2. Description of Related Art
Ga.sub.1-x In.sub.x Sb/InAs superlattices are candidate materials for future generation infrared detectors and lasers from mid- to very long-wavelengths (3 to 5 .mu.m and beyond). The optimum substrate temperature (as determined by surface morphology and x-ray diffraction) for fabrication of these superlattices by molecular beam epitaxy is below 400.degree. C.; see, e g., D. H. Chow et al, "Growth of InAs/Ga.sub.1-x In.sub.x Sb infrared superlattices," Journal of Crystal Growth, Vol. 111, pp. 683-687 (1991); I. H. Campbell et al, "Far-infrared photoresponse of the InAs/GaInSb superlattice", Applied Physics Letters, Vol. 59 (7), pp. 846-848 (1991); and J. L. Davis, "Optimum growth temperature determination for GaInSb/InAs strained layer superlattice", Journal of Vacuum Science and Technology B, Vol. 11, No. 3, 861-863 (May/June 1993).
The Chow et al publication outlines a molecular beam epitaxy (MBE) growth procedure which yields Ga.sub.1-x In.sub.x Sb/InAs superlattices with good surface morphology, but poor photoluminescence efficiency and high background doping levels. Photoluminescence efficiency (as it relates to minority carrier lifetime) and low background doping are both key material properties for the realization of high performance optical and electronic devices such as infrared detectors and lasers.
Thus, there is a need to provide GaInSb/InAs superlattice materials having improved photoluminescence efficiency and low background doping.